Lubricating- abrasive wheel and method of making the same



UNITED STATES PATENT OFFICE.

LEON L. KATZENSTEIN, OEWORCESTER, MASSACHUSETTS, ASSIGNOR TO NORTON COMPANY, A CORPORATION OF MASSACHUSETTS.

' LUBRICATING- ABRASIVE WHEEL AND METHOD OF MAKING THE-SAME.

No Drawing.

To all whom it may concern:

Be it known that I, LEON L. KATZENSTEIN, a citizen of the United States of America, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Lubricating Abrasive Wheels and Methods of Making the Same, of which the following is a full, clear, and exact specification. I

In the art of grinding surfaces by means of abrasive Wheels, it is often desirable to fill the pores. of a wheel with a suitable lubricant, such as waxes, greases, oils and fats, which is not hardened by heat like a wheel bond, in order to lubricate the wheel and decrease the friction of grinding and therefore decrease the heat generated and the power required during the operation. A

lubricant furthermore prevents loading of metal particles in the face of the wheel, because the pores thereof are already part-1y filled and because the metal beingg'round I ,doesnot readily get hot and form soft globwheel.

ules or particles capable of adhering to the walls of the pores. These lubricating fillers also appear to have the property of allowing the abrasive particles to penetrate deeper" into the work and therefore out faster, the greater strain upon the cutting particles causing them to break off more readily and therefore prevent glazing of the face of the Wheels filled with such materials. have, however, proven unsatisfactory for many *types of grinding operations, due to the fact that preferred wheel fillers do not have any large adhesive properties and tend melt un'derthe heat of grinding and to 40;"

constantly-thrown centrifugally from the rotatingv wheel on to the operator and adjacent articles as the wheel wears away. Depending. upon the character of the material-used,

the filler may volatilize under the heat and 1'5- mayfeven; burst into flames. Hence, in cergive-ofi an; objectionable odororsmoke, and

tain types, of grindingwhich may involve acons'i'derable evolution of heat," operators I limiting these otherwise satisfactory wheels Specification of Letters ratent.

it after a few minutes.

Patented Dec. 16, 1919.

Application filed December 8, 1917. Serial No. 206,334.

to grinding operations which produce only a low heat at the point of contact.

It is accordingly an object of my invention to eliminate the above disadvantages and to provide a self lubricating, non-spattering abrasive wheel of great utility in fields heretofore prohibited because of the detrimental eflects noted, and which contains'the maximum amount of an easily melted, nonbonding, lubricating filler, capable of mak ing the wheel cooler acting, which will not becentrifugally thrown from the wheel to an objectionable extent under normal grinding. conditions. With this and other obties of the abrasive wheel, the p'arafiin remains melted in the wheelpores into which it has penetrated for some time after the wheel has been removed from the path, and, in accordance with the old method, is

drained first from one circular side andy then from the other by placing the hot wheel upona suitable support and reversing In this manner, all of the excess filling material which is not held by capillary attraction or by the attraction of the pore walls for the molten material is eliminated. However, an ,msufficient amount has been removed, smce only that force involved v in the attraction of gravity has been utilized, while the centrif ugal force acting upon the rapidly rotating wheel during grinding. is much larger'and can easily overcome the attraction of the pore walls for thefiller after it has been melted by the; heat of grinding. It is accordingly the main purpose ofmy invention to eliminate this excess filler material which is [1 00 thrown outcentrifugally and to make a. lu-

I filled.

bricated abrasive wheel more useful in the art of grinding. In the practice of my invention, I accordingly lncorporate into the pores of a previously bonded abrasive body a lubricating sfiller in'fiuid condition, as for example molten or in solution, the filler to be one which is not chemically changed or hardened by heat into an adherent Wheelstrengthening bond, but which after solidification will tend to soften under heat and cause the wheel to tatecl wheel, I initially eliminate from the wheel pores substantially all that excess 'material which would be thrown out centrifugally during grinding, but would ordinarily be retained while fluid against the attraction of gravity. For this purpose I employ a force of sufiicient magnitude to counteract the capillary attraction of the pore walls for the filler, and obviously may use various principles -or methods of operation. While such means as a jet of steam or gas or a vacuum may be employed, I prefer to use centrifugal force, since it can be easily regulated and conditions readily duplicated, and since it involves similar efi'ects upon the wheel to those caused by rotation during grinding.

As a simplified method of incorporating the right amount of filler, in a wheel, I may heat the wheel, as by means of an oven, to a temperature preferably higher than the melting point of the filler .to be used,- e. g. parafin,and dip the hot wheel into filler previously melted until the pores have taken up the full amount, or as much as is determined by practice to be desirable. The wheel is then mounted upon bearings while hot and while the parafin is still molten and is rapidly rotated until the centrifugal force generate has eliminated substantially all of that excess of filling material which would be thrown out under the heat of the actual grinding operation, it being obvious that a large proportion of the filler is permitted to remain in the pores.

For example, a pre-heated twelve-inch vitrified aluminum .oxid wheel of medium grit and grade'may be immersed in molten parafin until the pores are substantially The wheel is then immediately mounted on an'arbor and rotated, beiiore the paraffin has hardened, at a gradually increaslng speed until the rate'is about 3,000 surface feet per minute, the rotation being ordinary the centrifugal'force and heat involved in neaenoe continued; for about three minutes. It is found that a wheel treated in this manner may be utilized for grinding at a rate of 5,000 surface feet per minute more or less, depending on the character of the work beingground, without the paraifin spattering from the wheel to any material extent. This rate of rotation employed in removing the excess filler may be considerably less than the normal speed employed in grinding, depending upon the temperature and the fluidity of the filler in the pores, as well as exterior conditions such as the temperature of the room and the character of the .work to be ground. While it is desirable to mount the wheel upon hearings in its normal rotating position, it is of course obvious that it may be mounted in any other desired fashion and rotated in any manner by any suitable means.

In accordance with this invention, I eliminate sufiicient of the excess filler to make the wheel not only unobjectionable for all creased utility in new fields, and I provide therefor a simple and economical manner of filling the wheel to the required amount with suflicient lubricant for all practical purposes and at the same time eliminate the labor and time consumed heretofore in turning the wheels and draining out the excess filler, in accordance with the old practice. p Having thus described myinvention, what I claim as new "and desire to secure by Letters Patent is:

1. A non spattering, selflubricating inding wheel comprising a porous, coherent body of bonded abrasive material and a lubricating non-bonding filler, capable of readily softening under the heat of grinding and making the wheel cooler acting, which is incorporated in the' pores of the body and substantially all of which permanently adheres to the pore walls when subjected to the normal grinding operation.

2. The method of making a non-spattering, self-lubricating grinding wheel having a porous body .of bonded abrasive grain comprising impregnating the pores of the body with a lubricating non-bonding material in fluid condition and then, while said material is fluid, forcibly removing from the pores substantially all of that excess material which, after solidifying, will not be permanently retained within the pores under the centrifugal force and frictional heat generated in a normal grinding operation.

3. The method of making a non-spattering, self-lubricating grindin wheel having a porous, coherent body 0 abrasive material, comprising heating said wheel body and impregnating the pores thereof with a molten lubricant, maintaining the lubricant in a fluid condition, rotating said body at-a grinding uses but of greatly ini velocity, less than the normal grinding rate for which the Wheel is adapted, which Will remove substantially all of that excess of lubricant Which would not be permanently retained, after solidification, under the centrifugal action and heat generated in the normal grinding operation, maintaining said rotation until said excess of material has been removed and cooling the wheel body to solidify said lubricant Within the .Wheel 10 pores. Signed at Pittsburgh, Pennsylvania, this 30th day of November, 1917.

LEON L. KATZENSTEIN. 

